In earlier guides, we discussed how it doesn’t seem likely that saturated fat is to blame for heart disease, and the Cholesterol Hypothesis leaves a lot of unanswered questions.
We also discussed that a much more plausible theory is the Blood Clotting Hypothesis. This theory suggests that heart disease develops by the process of an increased rate of endothelium damage alongside blood clotting over many years.
Every person is unique and, as this guide will demonstrate, there’s no single cause of heart disease. However, there are many factors that might accelerate or slow down this process.
By the Blood Clotting Hypothesis, the main goal when trying to prevent heart disease is to protect the endothelium layer and/or reduce the rate of blood clots.
This guide will explore some of the factors thought to affect heart disease to see if they fit in with the Blood Clotting Hypothesis. We will then suggest some practical tips that you can easily incorporate into everyday life.
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Exercise
Does it fit with the Blood Clotting Hypothesis?
Exercise is one of the factors that all experts agree can reduce your risk of heart disease. Evidence suggests that there’s a strong, negative dose-response relationship between exercise and heart disease. This means that as the amount of exercise increases, the risk of dying from heart disease decreases.
Research suggests that exercise helps to repair and protect the endothelium layer, prevent unnecessary blood clotting, and relax the artery walls. So it seems that exercise positively impacts every step of the process that leads to heart disease, according to the Blood Clotting Hypothesis. Increasing elasticity of the arteries also results in reduced blood pressure.
The British Medical Journal published a large meta-analysis of research that compared high-intensity intermittent training (HIIT) with lower-intensity, longer periods of exercise in individuals living with chronic diseases. Results indicated that HIIT was more beneficial to heart health than lower-intensity, longer periods of exercise.
The research suggested that when short bursts of exercise are of a high enough intensity, it promotes elasticity of the arteries more so than longer, steady periods of exercise.
Practical tips
If you’re relatively new to exercise, here are 10 simple ways to add short bursts of exercise into your daily routine:
- Do 1 minute of star jumps when you wake up in the morning
- Do 1 minute of squats in your lunch break
- Go up and down the stairs at work in your lunch break
- Do squats while brushing your teeth
- Try wall push-ups while waiting for the kettle to boil
- Do star-jumps during an ad break on tv
- Try leg raises in your chair at work
- Do step-ups when you’re talking on the phone
- Jog on the spot while waiting for the bus to arrive
- Jog on the spot for 1 minute as soon as you get home.
Key points:
- Exercise is one of the undisputed factors that greatly reduces your risk of heart disease.
- Exercise, particularly in short, high-intensity bursts, protects the endothelium layer, reduces the rate of blood clots, and relaxes the artery walls.
- Try including some short bursts of exercise in your daily routine.
Sunlight and vitamin D
Does it fit with the Blood Clotting Hypothesis?
Vitamin D is known as the sunshine vitamin. Our bodies produce it when we’re exposed to sunlight, and it’s very beneficial for bone health and immunity. However, supplementation of vitamin D doesn’t appear to have the same beneficial effects as sunlight exposure on heart disease risk. A large meta-analysis of good quality studies suggested that vitamin D supplementation didn’t reduce the risk of heart disease.
However, a very large observational study from Sweden, suggests that exposure to sunlight reduces the risk of heart disease in women. Although observational studies can’t be used to show causation, this study was extremely large (nearly 30,000 participants) and was followed up after 20 years, which strongly suggests there’s a link.
On top of this, recent research from The University of Edinburgh suggests that UV light (which we get from natural sunlight) reduces our risk of heart disease. The findings demonstrate a dose-response relationship between UV light exposure and nitric oxide synthesis (which relaxes the muscles in the artery walls, and prevents the blood clotting unnecessarily).
Interestingly, this study didn’t find a reduction in blood pressure, despite the evidence suggesting UV light relaxes the muscles in the artery walls. The researchers gave the explanation that the increase in nitric oxide was not sustained for long enough to show a reduction in blood pressure, due to the way the UV light was delivered to participants. Plus, other randomised clinical trials from the same University demonstrate a reduction in blood pressure following exposure to UV light.
Overall, there’s strong evidence suggesting that exposure to natural sunlight reduces our risk of heart disease, rather than supplementing vitamin D, which fits in with the Blood Clotting Hypothesis. When we’re exposed to sunlight it increases the synthesis of nitric oxide, which relaxes the muscles in the artery walls, and prevents the blood clotting unnecessarily.
Practical tip
- Get outside as much as possible
Whether it’s doing some gardening at the weekend, playing sports, or going for a walk during your lunch break, try to be outside where possible. If you’re on holiday and it’s sunny, aim to get a bit of sun exposure each day. Children and those with fair skin, however, should be more careful and enjoy shorter moments of exposure to the sun to avoid skin damage.
This seems like controversial advice, given the skin cancer scares in the media recently. However, the rising numbers of those diagnosed with skin cancer appear to be a result of a change in how the condition is diagnosed.
On top of this, a study from the USA suggests that sun exposure is actually linked to increased survival rates for those who are recovering from skin cancer. So, although sunburn is dangerous, general exposure to the sun in moderate amounts doesn’t seem to pose any huge risks and is beneficial for heart health.
Key points:
- Natural sunlight, rather than vitamin D supplementation, appears to reduce the risk of heart disease.
- Sunlight relaxes the muscles in the artery walls, and prevents the blood clotting unnecessarily.
- Try to be outside as much as possible to increase your sun exposure (while avoiding sunburn).
Potassium
Potassium is a mineral found in many different foods. A large observational study, called the Scottish Heart Health Study, looked at 27 different factors all thought to be related to heart disease in some way. Results suggested that high potassium intake was protective against heart disease and reduced death by any cause.
Interestingly, many traditional risk factors for heart disease, such as cholesterol and body weight, didn’t appear as a significant risk factor in this study.
Although this data is observational, many other large observational studies suggest that potassium intake reduces our risk of developing heart disease. Only when many large observational studies show the same associations, we can start to consider that one factor causes another (in this case, potassium causes a reduction in heart disease death).
Evidence suggests that potassium increases the synthesis of nitric oxide. As we discussed, this relaxes the muscles in the artery walls and prevents the blood clotting unnecessarily. So it appears that the research on potassium does fit in with the Blood Clotting Hypothesis.
Practical tip
- Eat a balanced diet
We don’t need a huge amount of potassium to see the protective effects. If you aim to eat a balanced diet, you will naturally be eating foods high in potassium, such as spinach, lentils, broccoli, bananas, and sweet potato.
If you’re unable to eat a variety of foods, then a supplement might be a good idea, but is unnecessary for most individuals. However, if you’re on medication or are living with kidney disease, potassium supplementation might be dangerous and you should consult with your medical team.
Key points:
- Potassium appears to reduce the risk of heart disease.
- Potassium relaxes the muscles in the artery walls, and prevents the blood clotting unnecessarily.
- Aim to eat a balanced, varied diet with foods such as spinach, lentils, broccoli, bananas, and sweet potato.
Stress
Does it fit with the Blood Clotting Hypothesis?
Stress is a difficult thing to measure as it’s usually caused by external factors and stress affects everyone differently. For example, some people enjoy public speaking and get a thrill out of it, whereas it’s a nightmare for many others. On top of this, the same individual might react differently to the same external stress depending on how they are feeling that day.
So when we’re talking about ‘stress’, we really mean the individual’s response to stress, which might be better defined as ‘strain’.
Stress, or more accurately ‘strain’, can increase our risk of developing heart disease.
One researcher, called Björntorp, figured out that you can objectively measure strain by looking at peoples’ hypothalamic-pituitary-adrenal (HPA) axis. The HPA axis regulates our stress response and causes fluctuations in certain stress hormones, such as cortisol.
He showed that in a healthy person, cortisol fluctuates throughout the day, whereas an unhealthy cortisol release looks more like a flat line with minimal change throughout the day.
Björntorp suggested that this is a result of the HPA ‘burning out’, as when people are repeatedly exposed to negative strain they start to show a flat line cortisol response.
When you have unhealthy cortisol activity, it triggers many different biological responses, which either increase endothelium damage or stimulate blood clotting. So, it seems that the research on stress fits in with the Blood Clotting Hypothesis.
Practical tips
So what can we do to reduce our stress levels? There are many different habits that we can introduce to try and tackle stress. However, focussing on one habit at a time is more effective than trying to tackle multiple aspects.
Meditation and breathing can hugely impact your stress levels. A study demonstrated that a 3-day crash course in meditation reduced the activity in the brain region that processes stress (the amygdala).
Deep breathing is one of the habits we encourage on the Second Nature programme. This can be a good way to ease ourselves into the habit of meditating. We can include it in our daily routine, for example, when you’re waiting at the bus stop, try taking 2 minutes of deep breathing.
Key points:
- Stress is better defined as ‘strain’ (our response to stress).
- Consistent strain increases our risk of developing heart disease.
- Abnormal cortisol activity (stress hormone) leads to endothelium damage and stimulates blood clotting.
- Deep breathing is a great way to try and reduce your stress levels.
Type 2 diabetes
Does it fit with the Blood Clotting Hypothesis?
There’s an established link between type 2 diabetes and heart disease. Individuals living with type 2 diabetes are 2-3 times more likely to develop heart disease.
One theory as to why type 2 diabetes increases the risk of developing heart disease is that consistently high blood glucose levels damage the endothelium layer.
There’s a slippery, slimy coating inside our blood vessels, lining the endothelium layer, called the Glycocalyx, that looks like a billion tiny hairs under a powerful microscope. The function of this coating is to protect the endothelium layer from damage and prevent the blood clotting unnecessarily.
Research, published by the American Diabetes Association, suggests that high blood glucose significantly reduces this protective coating, resulting in damage to the endothelium layer and an increased rate of blood clotting.
Overall, it seems that the large increase in the risk of developing heart disease for individuals living with type 2 diabetes can be explained by the Blood Clotting Hypothesis.
Practical tips
As type 2 diabetes increases the risk of developing heart disease, reducing the risk of type 2 diabetes would naturally reduce your risk of heart disease. Similarly, if you’re living with type 2 diabetes, better management of the condition would reduce your risk of heart disease.
Type 2 diabetes is characterised by consistently high blood glucose, so maintaining stable blood glucose levels is key to preventing or managing the condition.
As carbs have the biggest impact on our blood glucose levels, reducing our intake of carbohydrate-containing foods will reduce the amount of glucose entering the bloodstream in the first place.
Recent studies have found consistent benefits in improved blood glucose control, weight loss, and sustained medication reduction when participants followed a low-carb diet. It’s also been shown that the low-carb diet had a high adherence rate after 12 months, suggesting it’s a more sustainable way of eating in the long run.
Regular exercise, particularly resistance training or high-intensity short bursts, can also help to control blood glucose levels by increasing insulin sensitivity. High insulin sensitivity allows our body to use up blood glucose more effectively, resulting in lower blood glucose levels.
Key points:
- The increased risk of heart disease for those living with type 2 diabetes can be explained using the Blood Clotting Hypothesis.
- Consistently high blood glucose levels damage the protective coating of the endothelium layer, resulting in more damage and blood clotting.
- A low-carbohydrate diet and regular exercise is the best way to prevent type 2 diabetes, or better manage the condition, and reduce the risk of developing heart disease.
Smoking
Does it fit with the Blood Clotting Hypothesis?
Smoking is one of the few factors that everyone agrees contributes to heart disease. Over time, plenty of large observational studies show a big effect of smoking on heart disease.
Although observational evidence can’t show causation, many studies have consistently shown that for both men and women, the risk of dying from heart disease was nearly double for smokers, compared with non-smokers.
Our risk of death from heart disease also seems to increase as exposure to smoke, how long we have been smoking, and the depth of inhalation increases.
Evidence suggests that smoking damages the endothelium layer, slows down the repairing process, and promotes blood clot formation. So it seems that smoking influences every step of the process that leads to heart disease, according to the Blood Clotting Hypothesis.
Practical tips
Obviously, if you don’t smoke then skip this section! However, if you do smoke and are wanting to cut down, speak to your doctor and try these tips:
1) Try reading a book that has helped other individuals quit
Many people have been able to quit smoking following the advice in Allen Carr’s book.
2) Consider a cognitive behavioural therapy programme
Quit Genius is a great app-based programme that offers personalised digital therapy to help you quit smoking.
3) Find a buddy
Research has shown that having a trusted buddy that you’re accountable to is an effective tool in making progress towards your goals. Try to quit together with a friend or family member, so you can encourage and support each other.
Key points:
- Smoking is one of the undisputed factors that greatly increases your risk of heart disease.
- Smoking damages the endothelium layer and increases the rate of blood clots.
- If you want to quit smoking, try following the advice of Allen Carr’s book or joining the Quit genius programme.
Take home message
- Many of the factors that affect heart disease fit in with the Blood Clotting Hypothesis.
- Type 2 diabetes, stress, and smoking seem to increase your chances of developing heart disease.
- Exercise, potassium, and sunlight exposure appears to reduce your risk of developing heart disease.
